Baking the bread

Can anyone help me. I have been baking plain sourdough bread for about a year, now. I had great success with the no-knead recipes, but have decided to try some other recipes. When I tried to bake a sandwich loaf, the crust got very thick and hard. I decided to put the loaf pan and all, into my cast iron dutch oven and cook as I used to cook the no-knead. I set the temperature for 450, preheated the oven and dutch oven, popped the bread in it and set the timer for 30 minutes. At that time, I inserted a thermometer into the bread, and left it for a further 15 minutes. The internal temperature came up to 192 degrees, and never went above that, even though I left it in for another 30 minutes. Any comments or suggestions?